Test-retest reliability of 24 hours of activity monitoring in individuals with Parkinson's disease in home and community

Background/Objective. This study examined the test-retest reliability of an activity monitor (AM) in home and community settings in individuals with Parkinson's disease (PD). Methods. Nine independent community dwellers with idiopathic PD were recruited (8 males and 1 female; median age = 66 years, range 46-71; Hoehn & Yahr score 2). Patients wore the AM for 3 separate sessions in the home and community with 7 days between each session. The first 2 sessions lasted 24 hours each, and the third session lasted 48 hours. Reliability indices and measures of variability were obtained by using intraclass correlation coefficients (ICC) and generalizability coefficients. The functional activity measures included the percentage of time spent in sleeping positions, sitting, standing, and walking; the number of transitions between sit and stand; the total number of transitions; the number of walking periods lasting 5 and 10 seconds; and stride frequency. Results. The ICCs for functional activities between the first and second consecutive days for the 48-hour session (third session) ranged from .76 to .92. The ICCs for the 7- and 14-day intervals ranged from .45 to .96, with walking-related measures showing the highest ICCs (range = .81 to.96). Across the three 24-hour periods (sessions 1 and 2, and the First 24 hours of session 3), the ICCs for walking-related measures were again high ranging from.87 to.92. Walking-related measures demonstrated the highest generalizability coefficients, indicating these measures have the highest test-retest reliability in comparison to other functional activity measures. Conclusions. The present study shows that 24 hours of recording with an AM is a sufficient duration of time to reliably record patients' functional activity in the home and community settings. In addition, the highest test-retest reliability for activities across 7- and 14-day intervals were found for walking-related measures in individuals with PD, indicating these measures have the highest stability compared to the other measures of functional activity.